1) Field of the Invention
The present invention relates to an image information code processing system wherein bit pattern information expressing a 2-valued picture is compressed and coded for facsimile application and so on.
2) Description of the Related Art
As well known, one page of a document is sent under optical scanning by, e.g., 8 lines/mm and sampling intervals of 8 pixels/mm, to the scanning line in a facsimile. Therefore a large amount of digital image information included in a bit pattern obtained by the above scanning must be sent or stored.
Accordingly, various redundant compression coding systems have been developed; typical of which are those recommended as a facsimile coding standard by the CCITT (International Telegraph and Telephone Consultative Committee).
The recommendation shows an MH one dimensional coding system and an MR two dimensional sequential coding system.
In the MH system, a run-length coding for a bit pattern of 2-valued image information obtained along a scanning line compresses the information by conversion into a comparatively short codeword, combining continued bits having the same value.
In the MR system, a bit pattern along a scanning line is compared with a bit pattern along the adjacent next scanning line, and a difference bit pattern is obtained. The difference bit pattern is coded using the principle of the run-length coding, and by sequentially applying the same process, generally a higher information compression is obtained than with the MH system.
These compression coding systems can compress information to a certain degree as a general purpose system applied to various image information. However, these systems do not utilize a feature of the figure of the object image. If the features of the figure are considered, a higher compression of the information is possible. Thus, a coding system by which the above compression can be performed is desired.